The MessageVersion contains the versioning information both about the SOAP envelope and the addressing protocol that is used by a message. An instance of Message is bound upon creation to a specific MessageVersion by passing the version as a parameter into one of the CreateMessage overloads.

All the static "get" properties in this class, such as Soap11WSAddressing10 and Soap12 have enumeration-like semantics. They provide an enumeration of the possible message versions supported by the Windows Communication Foundation (WCF) runtime. A message has an envelope structure and an addressing structure. MessageVersion is just a shortcut for supplying {EnvelopeVersion, AddressingVersion} together.

There are currently two SOAP envelope versions available: SOAP 1.1 and SOAP 1.2. These versions of SOAP are represented by EnvelopeVersion and are returned by the Soap11 and Soap12 properties. The version of SOAP associated with the MessageVersion can be recovered by using the Envelope property. For more information, see the schema for SOAP 1.1 and SOAP 1.2.

There are currently two versions of WS-Addressing available. The one submitted on 10 August 2004 and the one specified in the WS-Addressing 1.0 protocol. The address version used by the current message version can be recovered using the Addressing property. These versions of WS-Addressing are represented by AddressingVersion and are returned by the WSAddressingAugust2004 and WSAddressing10 properties. The WS-Addressing August 2004 is retained as a legacy value. The 10 August 2004 W3C Member Submission for WS-Addressing is available at Web Services Addressing (WS-Addressing). The 17 August 2005 W3C Candidate Recommendation for WS-Addressing 1.0 - Core is available at Web Services Addressing 1.0 - Core.

None provides support for using "plain old XML" (POX)-style messaging. Enabling basic POX messaging is now a matter of setting up an HTTP binding on your service with a text encoder that uses None.

Message version objects can be created using specified versions of WS-Addressing and SOAP using one of the CreateVersion overloads.